1. Field of the Invention
The present invention relates in general to coolant pumping systems used with internal combustion engines or other vehicle power plants in automotive vehicles, and in particular to bearingless impeller-type coolant pump systems which have an easily decoupled in-line drive, and are specifically designed for use with internal combustion engines or other drive power plants in automotive applications.
2. Description of Related Art
In conventional water pump systems used on automobiles, a drive belt and pulley are used to provide the drive rotation to the coolant pump shaft. The coolant may be of any suitable type, such as the commonly used mixture of water and antifreeze. A chain and sprocket gear arrangement is sometimes used instead of a belt and pulley. Two sets of bearings are typically provided in the pump casing to resist the large external side load forces generated by either of these drive arrangements. As is well known, when these side load forces are considered, the overall forces experienced by the pump shaft are inherently unbalanced. On account of the unbalanced force vector to the pump shaft, it is necessary to suitably strengthen the pump assembly, pump shaft and its ball bearings to handle expected loads and overloads. This adds to the cost and weight of the coolant pump.
A common failure mode for water pumps is the failure or wear of the water pump bearings. Severe bearing wear often results in damage to the flexible coolant shaft seal assembly, which allows coolant to escape from the engine's cooling system, thus presenting further problems. If the pump bearings did not fail in the first place, many such failures of the flexible shaft seal assembly could be avoided, along with the resultant loss of engine coolant, and destruction of the pump shaft on account- of scoring and galling.
To alleviate problems such as side load forces associated with conventional water pump systems on automotive vehicles, coolant pump systems have been developed which utilize an in-line shaft support assembly wherein the drive shaft is coupled, in-line, to the pump shaft of a conventional coolant pump. Typically, the in-line coupling between the drive shaft and the pump shaft is accomplished by providing the mating end of the pump shaft with a socket including internal splines and the mating end of the drive shaft with a male spline. Additionally, two sets of bearings are used along the length of the pump shaft to assist in reducing the side load forces. During operation, the drive shaft of the motor rotates a drive sprocket for a drive chain which is attached over and rotates the extending sprocket assembly. This in turn causes rotation of the impeller pump shaft thus driving the impeller pump.
One problem with coolant pump systems which utilize interconnecting splines to attach the impeller pump shaft and a drive shaft is the noise generated at times during operation. The dynamic forces exerted on this system cause the splines to oscillate or move relative to each other which can result in excessive noise under certain conditions. To alleviate some of this noise, it is known to spring load the sprocket assembly to limit the amount of oscillation between the splines. This system, however, is less than ideal in that male and female splined ends are expensive to machine, and the noise is merely limited, while the overall cost of the side load reducing drive system is substantially increased.
Accordingly, it would be very beneficial to provide an alternative side-loaded pump system which solves most, if not all, of the foregoing problems. It would be highly desirable to eliminate the noise generated by the splined connection. It would also be beneficial to eliminate the two sets of bearings typically provided in the pump housing which in turn would lower the costs.
In light of the foregoing problems with conventional chain-driven coolant pumping systems, it is a primary object of the present invention to provide a coolant pump arrangement for an internal combustion engine which eliminates the splined connection between the pump shaft and the drive shaft assembly, and replace it with an inexpensive reliable mechanical coupling that is easy to connect and disconnect repeatedly.
It is another object of the present invention to provide a bearingless coolant pump arrangement which eliminates the double bearing set typically provided in the pump housing.
It is a further object of the present invention to provide a bearingless coolant pump with an in-line drive shaft support assembly which very substantially reduces if not entirely eliminates the external side loads on the pump shaft.
One more object of the present invention is to provide an automotive coolant pump system with an in-line drive shaft support assembly and a coupling mechanism which allows the pump shaft to be quickly and repeatedly coupled and uncoupled from the rest of the in-line drive shaft support assembly by hand or by using simple hand tools.
Still another object of the present invention is to provide an-line drive shaft support assembly and coolant pump assembly, each assembly having a housing and a shaft, wherein the housings are slidably interconnected along a common axis to prevent any movement in a direction transverse to the axis, and wherein the drive shaft and pump shaft are slidably or threadedly interconnected for synchronous rotation and also to prevent movement therebetween in a direction transverse to the common axis.
Yet another object of the present invention is to provide a coolant pump assembly wherein a coolant overflow well or basin is provided within a drive shaft support housing, in order to avoid conventional dripping of coolant on the ground when it leaks in small quantities past the flexible shaft seal of the coolant pump upon start-up or at other times.
A further object of the present invention is to provide a coolant overflow hole adjacent to the coolant overflow basin within the housing for accepting excess coolant.